A little more than a month after announcing their engagement, the musically inclined couple swapped vows Saturday at the Encino home of the bride's parents, Joe and Tina Simpson, sources confirm to E! News.

"We're delighted to confirm that Pete Wentz and Ashlee Simpson were married this evening in front of family and close friends," a family rep told People.

JessicaSimpson, who served as Ashlee's maid of honor; her apparently still-willing beau, Tony Romo; Nicole Richie and Joel Madden; Scrubs star Donald Faison and his girlfriend, longtime Jessica pal and family friend Cacee Cobb; and Wentz's fellow Fall Out Boys were among the 100-plus guests in attendance.

Joe Simpson performed the nondenominational service, which took place about 7 p.m.

It's the first hitching for both the 23-year-old bride and her 28-year-old groom, who, sources have told E! News, are expecting their first child.

Simpson wore a wedding gown by Monique Lhuillier, accented with William Noble diamond-adorned necklace and earrings. Vera Wang took care of the bridal party dresses.

A source close to the Simpsons told E! News that many of the female guests painted their nails black and that "black or very dark" clothing dominated the fashion of many attending. The source described the entire theme as "goth-like" and "very unwedding like." A gothic cross on the altar reinforced the motif.

Jessica Simpson and Romo arrived a little after 11 a.m. and were joined shortly after by her longtime hairdresser and friend Ken Paves. Wentz showed around 2 p.m.

Guests were shuttled to the residence from a nearby parking garage.

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Security was so tight that one of Wentz's groomsmen was almost not let in. After talking to security and explaining that he was a last-minute substitution, the groomsman, dressed in a skinny-cut tuxedo and white shirt, was let into the party. Other guests were instructed not to bring cameras of any kind and even told not to bring in cell phones.

Paparazzi helicopters buzzed the compound, which is behind gates on a private drive, but large tents kept the festivities largely under wraps—to provide a modicum of privacy and, presumably, to ensure that People magazine gets its money's worth for the exclusive wedding coverage. (The magazine reportedly shelled out seven figures for the privilege).

By 12:45 a.m. the party began to wind down, and Jessica Simpson and Romo made their getaway. Most of the rest of the guests were gone by 1:15 a.m.

While some guessed the wedding was going to take place weeks ago to coincide with the release of Ashlee's latest album, Bittersweet World, far more evidence—such as dual bachelor/bachelorette parties on Thursday, a rehearsal dinner at her big sister's house Friday and delivery trucks swarming the Simpsons' homestead, one of which was hauling the cross-bedecked altar—pointed to a weekend celebration.

Event-planning staff and Simpson-family employees were seen flowing in and out of the house starting Thursday afternoon, while the tents were erected in the backyard and—over in the citified portion of Los Angeles—Wentz was spotted gassing up his car and fleeing Groom Watch 2008.

Having a wedding in the backyard was no easy task. As temperatures pushed 100 degrees in the Encino hills, biodiesel generators powered the air conditioning for the tents. Scaffolding decks and platforms had been erected for the dance floor and entertainment areas. Even fancy gray porta-pottys and a photo booth were trucked in.

Although the wedding itself seemed like a done deal, the venue was still relatively up in the air—to inquiring minds—until just a few days ago. But even with all the secrecy, the Simpson-Wentz wedding ultimately took place at mom and dad's house.

The couple announced their engagement April 9 in a message posted on FriendsorEnemies.com.

"We know there has been a lot of speculation recently about Pete and I and we wanted our fans to be the first to know, because you guys are the best. Yes, we are thrilled to share that we are happily engaged," Simpson wrote.

"Thank you for all of your support and well wishes—it means the world to us. We consider this to be a very private matter, and we wanted to be the first to tell you and to hear it straight from us."

Not so forthcoming have they been about their expectant status, with Wentz issuing a denial of sorts via email to MTV News and Simpson dodging questions right and left during her various recent media appearances.

Bump watch remains in full effect, but what with all this running around and location scouting, perhaps we all deserve a honeymoon.